The ad shows a clip of Heller at a press conference last year promising he would not support legislation that would take away health insurance from “hundreds of thousands of Nevadans.”

It adds that Heller “broke his promise” when he voted "yes" on a procedural vote to take up consideration of the Republican repeal and replacement plan, and when he voted yes on the “skinny repeal,” which would have repealed ObamaCare’s mandate to have coverage.

Heller did eventually vote "no" on the GOP repeal and replacement plan, though. Heller’s campaign shot back that the “new Rosen ad shamelessly lies about Heller’s record on pre-existing conditions.”

Heller’s campaign says the senator actually “stood up for Nevadans with pre-existing conditions” during the repeal debate last year, and noted that the “skinny repeal” he voted for did not touch ObamaCare’s protections for pre-existing conditions.

However, Heller has supported other legislation that does target those protections. The Rosen ad does not cite that.

Heller co-sponsored the Graham-Cassidy-Heller-Johnson bill, a newer GOP ObamaCare replacement plan, which would allow states to get waivers to allow insurers to charge people with pre-existing conditions higher premiums.

“Dean Heller’s vote to proceed with the House GOP’s health-care plan last year was a blatant broken promise and a deciding vote to advance a plan that would gut pre-existing conditions protections, and then he used that vote to introduce his own plan that would have eliminated the current federal guarantee of protections for pre-existing conditions,” said Stewart Boss, a spokesman for Rosen’s campaign.

Democrats have been on the attack over pre-existing condition protections in races across the country, hitting Republicans for their ObamaCare repeal votes.